Ultra high frequency oscillation circuits



lcii. 15 1940. gw. HANSELL y2,217,745

ULTRA' HIGH FREQUENCY OSQILLATION'CIRCUITS Filed March 20, 1934 2 Sheets-Sheet 1 I l O v @L4 M75/WA 5 AUX/MRY CdA/780.4

Y )4f/api Palm Jaa/raf aum/r INVENTOR C.W. HA SELL ATTORNEY Oct. 15 1940. c. w. l-uquusELl,

ULTRA HIGH FREQUENCY oscILLATIoN cIRcUITs Filed March 20, 1934 2 Sheets-Sheet 2 [Wm n SOURCE Y a l `l 1 yINVENTOR C.W. HA SELL.

i BY 7 W ATTORNEY Patented on. 15, 1940 e 2,217,745

UNITED STATES PATENT OFFICE ULTRA HIGH FREQUENCY OSCILLATION CIRCUITS Clarence W. Hansell, Port Jeierson, N. Y., ast signor to Radio Corporation of America, a corporation ol.' Delaware I I Application March 20, 1934, Serial No. 716,484

22 Claims. (Cl. 250.-17)

This inver'ition relates to high frequency oscil- 0de so as -to influence the movement of the eleclation generator circuits, and in particular to a trons emanating therefrom. method of and means for producing ultra high As is well known, the electrons which ordinarfrequency oscillations and modulating same; a ily tend to move in radial lines from the cathode,

primary object being to provide an oscillation when subjected to the action of a magnetic eld generator capable of producing kwaves having from coil 5 in a direction parallel to the cathode, 5 lengths as low as one centimeter. 0r at right angles to the electrostatic eld be- The invention, from a very broad aspect, comtween the electrodes and to the paths of the elecprises a magnetron type of oscillator tube with trons, willftend to move in spiral lines tangenlo concentric elements, wherein the electrons from tially to the anode as indicated by the arrows of the cathode are subjected toV the action of a magarcuate paths X and Y. As the strength of the lo netic eld in a direction parallel to the axis of magnetic field is increased these lines contract the cathode. The essential feature of the inventoward the cathode, and if the eld is made tion, however, resides in the use of an irregular strong enough, it will be apparent that none of cy1ind1'ica1 anode having an even number of regthe eleCtI'OnS Will reach the allde 3. If the ularly spaced portions which bend inward tostrength of the magnetic eld is decreased, howl5 ward the cathode. Other features lie in the parever, all of the electrons can be made to reach the ticular circuit arrangements used for taking anode. In accordance with the teachings of the from the oscillation generator the power gener- Present invention, the eld Strength and the 2o ated thereby and for modulating the oscillations value of the positive potential applied to the an- 2o obtained by suitable signal waves, and in the con- 0de 3 are adjusted to a critical value such that trol electrode employed in accordance with one the electrons just skim the inwardly bent D01- embodiment of the invention, for modulating the tions l of the anode and follow either the path oscillations produced by the generator. X 01 the Path Y, depending llDOn the POtential of 85 The following is a detailed description of the adjacent inward prOjeetlOnS 0f the anode.` The invention in conjunction with drawings, whereeleetrOnS. it Should be nOted, Will Strike an inin Figure 1 shows in cross-section a view of the Waldly Projecting anode DOltOn 4 When the adessential features of the oseiuation generator of jacent portions have a potential slightly in excess the invention, the arrows diagrammatically repof the positive applied potential; a posteriori, the

resenting the paths taken by the electrons under eleetrOnS d0 not reach these portions y4 when different conditions of operation, and Figures 2 their adjacent Sections are `less positive than the to 5, inclusive, show schematically diii'erent emapplied DOtentialbodiments of* complete circuit arrangements for In the production of oscillations, all the anode producing and modulating the desired ultra high current is made up of the electrons which strike frequency oscillations, in accordance with the the portions of the anode closest to the cathode, 35 invention. although most of the electrons ily in the curved The oscillation generator shown in Figure 1 path Y and return to the cathode. here is thus comprises an envelope l made of any suitable maobtained a condition of instability suitable for the terial, such as glass, containing within it a cen production 0f OSCIIatOnS- If, dile t0 thermal agl- 40 trally located electron emitting cathode 2, prefertation Which iS always present in a conductor not 4 ably of the heater type, and an irregular cylin. at absolute zero potential, or from other causes, ducal anode 3 having an even number of pob the potential of any projecting portion, such as tions 4 which are substantially or effectively anoqe pomt A', Uses above the average anode p0- spaced from one another by one ha1f wave length tent1al, the extra pull upon the electrons due to and which bend inward toward the cathode more the tnreased elctrostatic tierce exet'ted by the 45 or less m the manner shown in the gure. This condition at A will cause an increase 1n the number of electrons striking its adjacent point B anode 1s mamtamed at a positlve dlrect current t t. lh l um t1 hi h which will tend to makeB negative. Since po1nts p0 en la' avmg a va ue s men, y g to c ause A and B are designed to be a half wave apart anode current to set up the desired osclllations.

around the anode or an odd multiple of a half 50 A eld Coil 5 which may or may not employ iron wave, there will be a wave propagated around to aid its effect, surrounds the envelope and funcanode 3, from which it will be evident that a detiOnS t0 predllee an intense but COnStant magcrease in thepotential of B will be accompanied a netic eld which has iiux lines running through half cycle later rby a decrease in the potential of the envelope in a direction parallel to the cath- A. Thus, the disturbance caused by any fluctua- 55 tions in the potential of A or B tends to be reproduced cyclically in greater amplitude due to the mutual eiect of the portions upon one another. The waves of the disturbance are propagated around the whole anode 3 and continuous oscillations take place in such manner that when alternate projections of the anode have maximum positive potential, intervening projections will have minimum positive potential. Since the currents to the projections of the anode are always maximum when these projections have substantially minimum potential, the oscillations are self-sustaining, a pre-requisite for oscillation in any vacuum tube oscillator.

As the oscillations take place, the electron currents producing regeneration at point B are caused to fluctuate in different paths, such as X and Y indicated in the ligure, these fluctuations in path being chiefly due to fluctuations in the potential of A;

It should be noted, however, that the time of electron travel from a region where the potential. of anode projection A gives the electrons greatest acceleration to the point B is a factor in determining the oscillation eiliciency. This time may be governed by suitably regulating the anode to cathode potential and then adjusting the magnetic field to correspond, and may be made small compared to the time of a half cycle, or may be made to correspond to the time of a whole cycle, or multiples of a whole cycle.

If desired, power from the oscillator may be radiated directly, or oscillations produced may be carried o' through a transmission line suitably coupled to a portion of the anode. In the drawings, a two conductor line 6 serves the dual purpose of supporting the anode and of carrying oil' the power from the oscillator. l

Figure 2 shows a complete circuit arrangement for obtaining oscillations from the generator, modulating these oscillations with suitable signals, tuning the circuits to the oscillation frequency. and radiating the modulated oscillations. A suitable source of potential 'I supplies the two conductor line 6 with a positive direct current potential through a choke coil 8 to a point 9 on the line 6 which is at neutral potential with respect to the radio frequency oscillations. An adjustable tuning slider I0 in contact with both sides of the transmission line 6 and adjustably movable with respect thereto, functions to tune the frequency of the oscillations obtained from the anode 3. For modulating the oscillations there is connected to the transmission line 6 a modulator vacuum tube II to whose control electrode suitable modulation is supplied over line I2, the method of modulation shown being the well known Helsing system of modulation by means of which the potential of anode 3 is caused to vary in accordance with the variations in the modulation input over line I2. Any suit-l able utilization circuit, such as a dipole antenna I3 in the focus of a reflector I4 is coupled to the oscillation generator circuit. In this case the coupling is obtained through transmission line I5 which is in juxtaposition to the adjustable tuned slider I0. a mode of coupling which has been found to be satisfactory at the extremely high frequencies employed. If desired, tuning devices which may take the form of trombone slides I6 may be provided in both sides of the line I5 for adjusting the antenna circuit.

In Figure 3 there is shown a different type of antenna system and a different way of modulating the oscillations produced by the generator. In this particular figure, modulation is obtained by means of a series transformer to which is connected two vacuum tubes I1 and I8 of a class B modulator amplifier. The antenna 22 has been found to be particularly useful in the transmission of ultra short wave oscillations of the type desired and is more adequately described in United States Patent No. 2,099,296, granted November 15, 1937, on an application led December 23, 1933, by Philip S. Carter. For matching the impedance of the antenna'to that of transmission line I5 there is herein shown a reactance coil I9 in shunt across the line whereby the impedance of the antenna, the reactance coil and the portion of the line between the antenna and reactance coil match the impedance of the remaining portion of the line I5. If desired, a loop of wire or linear conductors may be used as an inductance, to replace the coil.

Figure 4 shows still another method of modulation by means of a modulator tube 20 which is inserted in series with the anode return circuit between the cathode 2 of the oscillator and the anode 3. Here, also, there is shown an impedance matching coil I9 for matching the line to a suitable dipole antenna I3. In this figure, however, the transmission line I5 is shown connected directly to the adjustabletuning slider I0 instead of being electromagnetically coupled thereto, the two sides of line I5 being coupled to spaced points on the slider lll'whereby the impedance of the slider in circuit 6 matches that of the line I5 or obtains correct conditions of loading.

Figure 5 illustrates a still further method of modulating the oscillations produced by the oscillation generator. In this figure there is provided an auxiliary control grid 2I which surrounds the cathode 2 and to which the modulation input circuit is coupled. The antenna here employed is of the directive V type and, although different from the dipole of Figure 4, is connected to the tunable slider in a manner similar to that shown in Figure 4. Modulation may also be obtained by varying the current through the field coil 5, although it is preferred to use any of the other methods shown in the figures.

Although the invention has been described in connection with the generation of oscillations having wave lengths down to one centimeter, it is to be understood that the invention is not limited thereto, since oscillations which are much longer than one centimeter may be obtained by following the teachings of the invention.

It will also be understood that the physical dimensions of the tube and circuits may be altered to obtain the most eflicient results. For example, such points as A and B of the anode in Figure l may be brought much closer to the cathode than has been shown in the drawings. In practice it is also possible to obtain modes of oscillation where the distance along the anode from points such as A and B in Figure 1 is effectively an odd or even multiple of a half wave length, as even fractions of these multiples. It is known that a great variety of modes of oscillation are theoretically possible with a tube construction such as has been shown. The tube of the invention may also be used as an ordinary magnetron oscillator similar to the operation of the simpler type of tube such as, for instance, is described in United States Patent No. 1,860,114, granted May 24, 1932, to Kinjiro Okabe.

I claim: i

1. The method of operating an electron discharge device comprising an electron emitting cathode and a continuous anode, said anode having a plurality of regularly spaced projections, which includes producing an emission of electrons from said cathode, subjecting said electrons to the action of a iield in such a way that they will move in spiral lines around said cathode, and collecting a portion of said electrons on only those projections of the anode which are at substantially minimum potential relative to the other projections.

2. An electron discharge device comprising a cathode and a continuous anode surrounding said cathode, said anode having an even number of regularly spaced portions bent inwardly toward said cathode, said portions being spaced apart from one another by a distance equal to approximately an odd multiple of half the operating wave, and means for producing a magnetic eld with ux lines runningv parallel to said cathode.

3. An oscillation generator comprising an evacuated envelope containing a centrally located cathode, and a continuous anode surrounding said cathode, said anode having an even number of regularly spaced triangular shaped portions bent inwardly toward said cathode, the innermost parts of said portions being spaced from each other by a distance approximately equal to an odd multiple of half the operating wave, and a coil around said envelope for producing a iield in a direction parallel to said cathode.

4. An electron discharge device comprising a cathode, and an .anode surrounding said cathode, said anode having an even number of regularly spaced portions bent inwardly toward said cathode, said portions being spaced apart from one another by a distance equal to approximately an odd multiple of half the operating wave, a control grid intermediate said cathode and anode, and means for subjecting the electrons emanating from said cathode to a magnetic field in a direction parallel to said cathode.

5. An oscillation generator comprising an electron discharge device having a cathode and a continuous anode surrounding said cathode, said anode consisting 'of an even number of regularly spaced portions bent inwardly toward said cathode, said portions being spaced apart from one another by a distance equal to approximately an add multiple of half a wave, a coil surrounding said device for subjecting the electrons emanating from said cathode to a magnetic eld in a direction parallel to said cathode, and means for modulating the oscillations produced.

6. In combination, an oscillation generator comprising an electron discharge device having a cathode, and an anode surrounding said cathode, said anode consisting of an even number of regularly spaced portions bent inwardly toward said cathode, said portions being spaced apart from one another by a distance equal to approximately an odd multiple of a half wave, means for subjecting the electrons emanating from said cathode to a magnetic field in a direction parallel to said cathode, an output circuit, a two conductor line directly connected to said anode for coupling said output circuit to said anode, and a source of positive potential connected to said line at a neutral point for radio frequency potentials.

"1. In combination, an oscillation generator comprising an electron discharge device having a cathode, and an anode surrounding said cathode, said anode consisting of an even number of regularly spaced portions bent inwardly toward said cathode, said portions being spaced apart from one another by a distance equal to approximately an odd multiple of a half wave, means for subjecting the electrons emanating from said cathode to a magnetic field in a direction parallel to said cathode, an antenna, a short-circuited two conductor line directly connected to said anode for coupling said antenna to said anode, and a source of positive potential connected to said line at a neutral point for radio frequency potentials, and means for modulating the oscillations generated by said electron discharge device.

8. An electron discharge device comprising a cathode, and an anode surrounding said cathode, said anode having an even number of regularly spaced portions bent inwardly toward said cathode, said portions being spaced apart from one another by a distance equal to approximately a multiple of half a Wave, a control grid intermediate said cathode and anode, and means for subjecting the electrons emanating fromsaid cathode to a magnetic field in a direction parallel to said cathode.

9. An electron discharge device comprising a cathode, and a continuous substantially cylindrical anode, said anode having an even number of regularly spaced portions bent inwardly toward said cathode, said portions being spaced apart from one another along said anode by a distance electrically equal to approximately a multiple of a half wave length, and means for subjecting the electrons emanating from said cathode to a field in a direction parallel to said cathode.

10. An electron discharge device comprising a cathode and a continuous substantially cylindrical anode, said anode having an even number of regularly spaced portions bent inwardly toward said cathode, said portions being spaced apart from one another along said anode by a distance electrically equal to approximately a multiple of a half wave length, and means for subjecting the electrons emanating from said cathode to a field in a direction parallel to said cathode, a shortcircuit parallel wire system connecting said anode to a source of positive potential, means for tuning said parallel wire system, and an output circuit coupled to said parallel wire system.

11. A system in accordance with claim 10, characterized in this that said last means comprises a movable low impedance bridge connected across a parallel wire system.

12. An electron discharge device comprising a cathode and a continuous anode surrounding said cathode, said anode having an even number of regularly spaced target portions for collecting the electrons emanating from said cathode, said target portions being spaced apart from one another by a distance equal to approximately a multiple of half the operating wave and being substantially symmetrically positioned with respect to said cathode, each of said target portions being conductively connected to its adjacent target portions located on both sides thereof, and means for producing a magnetic field in a direction parallel to said cathode.

13. An electron discharge device comprising a plurality of electrically separate electrodes, one of said electrodes having a grooved portion remote from another of said electrodes constituting an inductance which together with the capacitances between said electrically separate electrodes forms a tuned circuit.

14. An electron discharge device comprising a cathode and an anode cooperatively disposed with respectl to said cathode, said anode having an electron receiving portion in proximity to said cathode and a grooved portion spaced from said irst portion forming an inductance which to gether with the interelectrode capacitances constitutes a tuned circuit.

15. An electron discharge device comprising a cathode and an electrode cooperatively disposed with respect to said cathode, said electrode having a portion disposed about said cathode and having also another portion removed from said cathode forming a substantially cylindrical inductance which together with the interelectrode capacitances constitutes a tuned circuit.

16. An electron discharge device comprising a cathode, and an anode having electron receiving surfaces disposed about said cathode, said anode having also a plurality of longitudinal grooves in its inner walls, disposed remote from. parallel to and symmetrical with said cathode, the portions of said anode bounding said grooves forming inductances which together with the capacitances between said anode and cathode constitute a tuned circuit.

17. A magnetron comprising a cathode, an anode, and means for producing a magnetic ield about said cathode, said anode having portions constituting an inductance and having surfaces separate from said portions and in juxtaposition to said cathode forming capacitances with said cathode.

18. A magnetron comprising a linear cathode, a cylindrical anode symmetrically disposed about said cathode, and means for producing a magnetic eld in the vicinity of and parallel to said cathode, said anode having a plurality of substantially cylindrical grooved portions in its inner wall forming inductances and having portions forming capacitances with each other and with said cathode, said inductances and capacitances forming a circuit resonant at the frequency at which the magnetron is intended to operate.

19. An electron discharge device comprising a cathode, and an anode cooperatively disposed with respect to said cathode, said anode having portions forming an inductance and other portions forming a capacitance with said cathode, and a pair of conductors secured to said anode at spaced points, said conductors serving as leads for an external circuit.

20. A magnetron comprising a linear cathode, an anode encompassing said cathode, means for producing a magnetic field in the vicinity of and parallel to said cathode, said anode having grooved portions symmetrically disposed with respect to said cathode and constituting inductances and having other portions constituting capacitances with each other and with said cathode, said grooved and other portions forming a tuned circuit, and a pair of conductors secured to said anode at angularly spaced points, said conductors serving as leads for an output circuit.

2l. A magnetron oscillator comprising an electron discharge device having an enclosing vessel containing an electrode having arms bounding a cavity and forming an inductance, said arms .terminating in juxtaposed parallel lines, and another electrode between said juxtaposed lines.

22. Electron discharge apparatus comprising a cathode and an output electrode, said output electrode having an irregular cylindrical electron receiving portion encompassing said cathode and dening an inductance, and having spaced portions forming a distributed capacitance in circuit with said inductance.

CLARENCE W. HANSELL. 

